1. Field of the Invention
The invention relates to a semiconductor equipment system provided with a support and positioning structure that comprises a first member and a second member and at least one motor.
The invention further relates to such support and positioning structure and to the use thereof.
2. Description of the Related Art
Support and positioning structures are widely used in semiconductor equipment systems, such as lithographic systems and inspection systems. In the case of a lithographic system, the first member is for instance a wafer stage onto which a semiconductor wafer may be attached. A typical example of a measurement system is an electron microscope. In order to achieve high resolutions as under development for lithography applications in the nanometer range, precise positioning is as much needed as the improved resolution of the optical or electro-optical system.
One example of such a system is known from U.S. Pat. No. 4,607,167. The known system is a charged particle beam lithography machine. The machine includes a column with an electron source, an illumination unit, a scanning deflector and a projection lens. This column is present within a vacuum envelope, so as not to disturb the electron beams. The positioning and support structure is present outside the vacuum envelope. This support structure comprising a first member with an exposed surface onto which a semiconductor wafer or a mask may be placed. Hereinafter, the term wafer is understood also to include mask. The structure further comprises a second member including an x-axis drive and an y-axis drive, as well as positioning sensors. Linear motors are preferably used for the translation in the x-y plane. Three independently controlled actuators are present between the first member and the second member. Both the distance of the wafer to the column as well as the angle in the z-x plane and z-y planes is therewith controlled. Hence, an accurate positioning is achieved. More recently, Lorenz motors have been proposed for the actuators between the first member and the second member. The projection lens is shielded against any electromagnetic fields originating from the actuators and linear motors through a shield directly around the working beam, i.e. an internal conical surface member of the vacuum envelope is fabricated from a ferromagnetic material.
It is a disadvantage of the known system that the vacuum environment is localized and does not include the positioning and support structure. The positioning of actual target surface outside the vacuum environment strongly increases the risk of mistakes when transferring a pattern to the target surface. This holds in particular for any system operating with charged particle beams, but also for any other system wherein a controlled atmosphere is used. A vacuum environment is proposed also for EUV (Extreme UV)-optical lithography systems. An environment with a lower pressure may well be required in various assembly steps, for instance for the formation of cavities with a controlled atmosphere such as needed for certain micro-electro-mechanical system (MEMS)-elements. The use of a portion of the vacuum envelope as shield in the known system makes that also another shielding design is needed.
Another example is known from U.S. Pat. No. 7,221,463. The known semiconductor equipment system comprises a support and positioning structure with a first and second member. The positioning structure specifically positions mirrors within a column of the equipment system. Linear motors are provided as actuators. Such motors typically comprise a coil and a permanent magnet, wherein the coil is provided on the second, fixed member and the permanent magnet is provided on the first, moving member. A spring for bearing the tare weight of the first, movable member is placed between the centers of the first member and the second member to alleviate the thrust force of the linear motor in the z-direction. This tare compensation spring is designed to have very small spring constants in a tare bearing direction and other five degree-of-freedom directions, so that transfer of vibrations from the second, fixed member through the spring to the first, movable member is almost negligible. The spring may for instance be a helical coil spring, but other embodiments are also possible. Cooling means may be present for cooling an optical element provided in the first, movable member. These are preferably provided in the second, fixed member, so that the optical element can be cooled in a noncontact manner. Noncontacting cooling means includes radiation cooling. A preferred implementation is cooling of a radiation member using a Peltier element, and cooling of the movable part using radiation from the radiation member.
It is a disadvantage of this known system that radiation cooling does not function adequate in vacuum or near-vacuum environments. Moreover, the use of a Peltier element in addition to radiation cooling complicates the equipment system. Such complexity is undesired and to be avoided unless strictly necessary.